diff --git a/ppadb/command/transport/__init__.py b/ppadb/command/transport/__init__.py
index 1adadf6..aeef77b 100644
--- a/ppadb/command/transport/__init__.py
+++ b/ppadb/command/transport/__init__.py
@@ -23,7 +23,7 @@ def shell(self, cmd, handler=None, timeout=None):
         conn.send(cmd)
 
         if handler:
-            handler(conn)
+            return handler(conn)
         else:
             result = conn.read_all()
             conn.close()